In a laser based white light source and especially in vehicle headlights, the light coming from the source (laser diode) has to be focused onto a light conversion device comprising a light converter like a phosphor. Usually, aspheric lenses are used for focusing. Additional optical elements (scattering device, lens array, mixing rod) are needed to shape the spot and the intensity distribution. The optical arrangement and alignment of the different optical elements is costly and limits miniaturization of the laser-based light source.
As an alternative to traditional lens collimators WO2012154446A1 mentions the possibility of using diffractive optical elements.